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The rising opportunities of sustainable tourism have brought many policies to control the exploitation of the environment and increase the reach of luxurious, safe, and authentic experiences to the different segments of tourists. This study seeks to prioritize the variables influencing the development of sustainable tourism and pinpoint key success factors that align with the Sustainable Development Goals (SDGs). It adopts a tri-dimensional framework encompassing economic, social, and environmental aspects, further delineated into eleven sub-dimensions, to provide a quantitative evaluation of sustainable tourism. We conducted interviews with 26 tourism industry experts hailing from eight countries, analyzing their responses using interval type-2 fuzzy sets. The results underscore the critical role of specific components in advancing sustainable tourism. In the economic dimension, "financial resources and tourism costs" emerge as vital factors. In the social dimension, "health and safety" takes center stage, while "green infrastructure" plays a pivotal role in the environmental dimension. These findings underscore the significance of these aspects in promoting sustainable tourism. Furthermore, this study explores the strategic importance of sustainable tourism equity in shaping tourism planning and development for emerging markets., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

This paper examines the impact of financial deepening on energy technology green innovation over the period 1996 to 2020. Utilizing the nonlinear QARDL technique, we assess the asymmetric short and long-term impacts across various quantiles. The research employs two measures of financial deepening, namely financial institution deepening (FID) and financial market deepening (FMD). The findings reveal that a positive change in the FID causes energy green innovation to rise, while a negative change in the FID causes energy green innovation to fall in the long run at most quantiles. Further, we find that the rise in the FMD help improves energy green innovation; however, the fall in the FMD does not significantly impact energy green innovation at all quantiles. Based on the findings, our research will help policymakers to develop valuable policies for financial deepening to enhance energy green innovation., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

China leads the world in freshwater pearl production, an industry in which the triangle sail mussel ( Sinohyriopsis cumingii ) plays a pivotal role. In this paper, we report a high-quality chromosome-level genome assembly of S. cumingii with a size of 2.90 Gb-the largest yet reported among bivalves-and 89.92% anchorage onto 19 linkage groups. The assembled genome has 37,696 protein-coding genes and 50.86% repeat elements. A comparative genomic analysis revealed expansions of 752 gene families, mostly associated with biomineralization, and 237 genes under strong positive selection. Notably, the fibrillin gene family exhibited gene family expansion and positive selection simultaneously, and it also exhibited multiple high expressions after mantle implantation by transcriptome analysis. Furthermore, RNA silencing and an in vitro calcium carbonate crystallization assay highlighted the pivotal role played by one fibrillin gene in calcium carbonate deposition and aragonite transformation. This study provides a valuable genomic resource and offers new insights into the mechanism of pearl biomineralization.

210 Po is a significant source of ionizing radiation that people are exposed to through food globally. This paper presents the wide range of accumulation level of 210 Po in the organs of two species of shellfish including freshwater mussel (Sinanodonta jourdyi) and golden apple snail (Pomacea canaliculata), common freshwater species in Vietnam. There was a significant correlation between 210 Po activity in muscle to their mass and size of freshwater mussels. In contrast, there was no relation between other organs of both species with their mass and size. The annual effective dose due to consumption of freshwater mussels ranged from 68.7 to 291 μSv year -1 with a mean value of 138 μSv year -1 for muscle and from 321 to 4560 μSv year -1 with a mean value of 1422 μSv year -1 for the hepatopancreas. Meanwhile, the AED for golden apple snail was recorded to be higher with values ranging from 105 to 2189 μSv year -1 with mean value of 673 μSv year -1 for muscle and from 468 to 4155 μSv year -1 with a mean value of 2332 μSv year -1 for hepatopancreas. Thus, the consumption of these two types of shellfish is considered relatively safe, but the hepatopancreas gland must be removed before processing., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Ammonia is a common toxicant in aquatic systems and one of the key factors affecting aquaculture. However, data on mollusks' toxic response and coping mechanisms to ammonia nitrogen, especially freshwater mollusks, are still lacking. In this study, we evaluated the tolerance of a freshwater mollusk Solenaia oleivora to ammonia and investigated its coping mechanisms by combining physiological, metabolic, and transcriptomic analyses in the gills. The acute toxicity test revealed that the LC50-96 h (temperature-20 ℃, pH-7.4) of ammonia in S. oleivora was 63.29 mg/L. The physiological and TUNEL results showed that although 10 mg/L ammonia exposure increased the activities of antioxidant, immune and ammonia detoxification-related enzymes, it still caused oxidative damage and cell apoptosis of gill tissues. A total of 97 differential metabolites (DMs) and 3431 differential expressed genes (DEGs) were identified after ammonia stress. Among them, most DMs and DEGs were involved in immune response, antioxidant, cell apoptosis, carbohydrate metabolism, amino acid metabolism, and lipid metabolism. The enhancement of glycolysis and lipid metabolisms may provide energy for immune response and ammonia detoxification. In addition, glutamine synthesis, alanine synthesis and urea cycle were involved in ammonia nitrogen detoxification in the gill tissue of S. oleivora. Our results indicate that ammonia leads to individual death in S. oleivora, as wells as oxidative damage, cell apoptosis, immune response, and metabolic changes of gill tissues. The findings will provide valuable information to assess the potential ecological risk of environmental ammonia to freshwater mollusks and theoretical guidance for the healthy aquaculture of S. oleivora., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

The incorporation of information and communication technologies in the power grids has greatly enhanced efficiency in the management of demand-responses. In addition, smart grids have seen considerable minimization in energy consumption and enhancement in power supply quality. However, the transmission of control and consumption information over open public communication channels renders the transmitted messages vulnerable to numerous security and privacy violations. Although many authentication and key agreement protocols have been developed to counter these issues, the achievement of ideal security and privacy levels at optimal performance still remains an uphill task. In this paper, we leverage on Hamming distance, elliptic curve cryptography, smart cards and biometrics to develop an authentication protocol. It is formally analyzed using the Burrows-Abadi-Needham (BAN) logic, which shows strong mutual authentication and session key negotiation. Its semantic security analysis demonstrates its robustness under all the assumptions of the Dolev-Yao (DY) and Canetti- Krawczyk (CK) threat models. From the performance perspective, it is shown to incur communication, storage and computation complexities compared with other related state of the art protocols., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Mutlaq et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Shells and pearls are the products of biomineralization of shellfish after ingesting external mineral ions. Bone morphogenetic proteins (BMPs) play a role in a variety of biological function, and the genes that encode them, are considered important shell-forming genes in mollusks and are associated with shell and pearl formation, embryonic development, and other functions, but bone morphogenetic protein 10 (BMP10) is poorly understood in Hyriopsis cumingii. In this study, we cloned Hc-BMP10 and obtained a 2477 bp full-length sequence encoding 460 amino acids with a conserved TGF-β structural domain. During the embryonic developmental stages, the cleavage stage had the highest expression of Hc-BMP10, followed by juvenile clams; the expression in the mantle gradually decreased with increasing mussel age. A strong signal was detected on epidermal cells on the mantle edge by in situ hybridization. In both the shell notching and inserting operations of the pearl fragment assay, we found that the expression of Hc-BMP10 increased after the above treatments. RNA interference assays showed that the silencing of Hc-BMP10 resulted in a change in the morphology of the prismatic layer and nacreous layer, with the prismatic layer less closely aligned and the disordered aragonite flakes in the nacreous layer. These findings indicate that Hc-BMP10 is involved in the growth and development of H. cumingii, as well as the formation of shells and pearls. Therefore, this study provides some reference for selecting superior species for growth and pearl breeding of H. cumingii at a molecular level and further investigation of the molecular mechanism for biomineralization of Hc-BMP10., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Construction activities may affect adjacent water systems by introducing increased levels of suspended solids into the water body and may subsequently affect the survival and growth of freshwater mussels. We tested three sediment types from sites in Missouri, including Spring River sediment (SRS), Osage River bank clay soil (ORC), and quarried limestone from Columbia (LMT). We prepared series of suspensions of each sediment with total suspended solids concentrations ranging from 0 to 5000 mg/L. Juveniles from three mussel species, Fatmucket (Lampsilis siliquoidea), Arkansas Brokenray (Lampsilis reeveiana), and Washboard (Megalonaias nervosa) were exposed to these suspensions in both acute (96-h) and chronic (28-d) tests. No clear impact on survival was observed from the acute or chronic exposures, but chronic test showed that juvenile mussels' growth was strongly affected. Interestingly, growth was enhanced at lower levels of SRS and ORC (≤500 mg/L, p < 0.05), and the juvenile mussels exposed to 500 mg/L SRS exhibited approximately 60 % more dry weight than those reared in the control. LMT did not enhance growth. Growth was slowed by high concentrations (>1000 mg/L) of all three sediments, implying that high suspended solids levels could reduce survival in the long term. Our findings may help to inform regulations and guidelines for construction activities to minimize adverse effects on juvenile mussels., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The US Geological Survey. Published by Elsevier B.V. All rights reserved.)

Caspase-3 is generally considered to be the most important terminal shear enzyme in the process of apoptosis, as well as an important part of cytotoxic T lymphocytes (CTL) killing mechanism, which is confirmed to play an important role in vertebrate cell apoptosis and immune system, and is poorly reported in invertebrates. In this paper, we used bioinformatics to perform amino acid multiple sequence alignment and protein structural domain analysis, and constructed a phylogenetic tree to identify the full-length cDNA of the cloned caspase-3 of Cristaria plicata (Named CpCaspase-3). The expression of caspase-1, caspase-7, caspase-8, and caspase-9 was found to be down-regulated by double-stranded RNA interference of CpCaspase-3 in C. plicata. Some degree of disruption of the caspase signaling pathway occurs. The expression of CpCaspase-3 was affected after injection of Lipopolysaccharide (LPS), Peptidoglycan (PGN), polyinosinic-polycytidylic acid (poly(I:C)), and Aeromonas hydrophila. These results were suggested that CpCaspase-3 was involved in the immune response of C. plicata. The wound recovery process of C. plicata was simulated and CpCaspase-3 was found to promote wound recovery. An autophagy inhibition and autophagy activation model of mussels was constructed, where apoptosis and autophagy undergo crosstalk, and inhibition of autophagy induces the onset of apoptosis, and similarly autophagy activation inhibits the process of apoptosis instead. In addition, a recombinant CpCaspase-3-pEGFP-C1 plasmid was constructed for subcellular localization experiments and found that CpCaspase-3 was distributed in both the nucleus and the cytoplasm. This paper aims to unveil the immune mechanism of C. plicata and provide a theoretical basis for the healthy culture of shellfish., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

In response to stress, cells can utilize several processes, such as the activation of the Nrf2/Keap1 pathway as a critical regulator of oxidative stress to protect against oxidative damage. C-Jun N-terminal kinase (JNK), a member of the mitogen-activated protein kinase (MAPK) family, is involved in regulating the NF-E2-related nuclear factor 2 (Nrf2)/antioxidant response element (ARE) signaling pathway. NAD(P)H quinone redox enzyme-1 (NQO1), a downstream target gene of the Nrf2 pathway, plays a vital role in removing peroxide and providing resistance to oxidative injury. We found that microcystins (MCs) stimulated CpNrf2 to express and increase anti-oxidative enzyme activities in a previous experiment. In our current study, the full-length cDNAs of JNK and NQO1 from Cristaria plicata (designated CpJNK and CpNQO1) were cloned. The relative levels of CpJNK and CpNQO1 were high in hepatopancreas. Upon MCs induction, the relative level of CpNQO1 was increased, whereas that of CpJNK was decreased significantly. In contrast, CpNrf2 knockdown upregulated the expression of CpJNK mRNA and phosphorylation of CpJNK protein (Cpp-JNK), but inhibited CpNQO1 expression. Additionally, we found that JNK inhibitor SP600125 stimulated expression of CpNQO1 and CpNrf2 upon exposure to MCs, and we further confirmed that CpNrf2 protein combined with the ARE element in CpNQO1 gene promoter in vitro, and increased CpNQO1-ARE-luciferase activity in a CpNrf2-dependent manner. These findings indicated C. plicata effectively alleviated MC-induced oxidative injury through JNK participated in regulating the Nrf2/NQO1-ARE pathway., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Despite an escalated gravity of interest in exploring factors that shape university students' social entrepreneurial intentions, there are significant gaps in our understanding of this phenomenon. The current study examines the boundary effects of religiosity and spiritual intelligence to predict university students' social entrepreneurial intentions. The authors collected the data from university students in their final years in multiple waves and employed SmartPLS (v 4.0) for data analysis. Our findings indicate that religiosity can affect social entrepreneurial intentions through two paths: intrinsic motivation mediates the association between intrinsic religiosity and social entrepreneurial intentions, and extrinsic motivation mediates the relationship between extrinsic religiosity and social entrepreneurial intentions. Further, spiritual intelligence moderates the relationship between intrinsic religiosity and social entrepreneurial intentions, mediated by intrinsic motivation such that at high levels of spiritual intelligence the association is more potent and vice versa. This is the first study that examines the boundary conditions of social entrepreneurial intentions of university students by employing the lens of religiosity and spirituality. The paper presents substantial theoretical and practical implications., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Jia et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Salinization of freshwater ecosystems due to anthropogenic sources will increasingly impact biodiversity. An example of point-source industrial salinization has occurred from historical activities at a U.S. Environmental Protection Agency Superfund Site near Saltville, Virginia USA and its associated chemical waste ponds adjacent to the North Fork Holston River. These point source discharges are documented contributors to mussel declines, partially due to high concentrations of chloride (Cl - , ≤ 26,000 mg Cl - /L) and potassium (K + , ≤ 97 mg K + /L). During a chronic 61-day laboratory study, Rainbow mussels, Villosa iris, were exposed to concentrations of Cl- (0, 416, 831, and 1,663 mg/L) and K+ (0, 4, 8, and 17 mg/L) to determine effects on survival and organ tissues. All test mussels died by day-2 in the 1,663 mg Cl - /L exposure, and 50% of mussels died by day-13 in the 17 mg K + /L concentration. Significantly greater abundances of tissue abnormalities were observed in digestive glands and kidneys with exposures to the 4 and 8 mg/L concentrations of K + versus the control, and significantly greater abundances of lesions in kidneys were observed in the 416 and 831 mg Cl - /L concentrations compared to the control. The sublethal effects to digestive glands and kidneys were below reported effect (EC 50, 20, 10 and LOEC) concentrations. Significant histological differences between control and baseline (day-0 sample) mussels were observed, suggesting the need for further study on the effects of captivity during longer-term laboratory experiments., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Assessment of human exposure to mixtures of non-persistent chemicals from food matrices and consumer products requires accurate characterization and estimation of their preceding exposure levels, and assessment sampling approaches for these varying chemicals remain disputable. Here, we used high-throughput targeted method to quantify urinary concentrations of 59 most common non-persistent chemicals (6 parabens, 14 bisphenols, 1 triclosan, 7 benzophenones, 2 dichlorophenols, 13 phthalate metabolites and 16 antioxidants) in 158 consecutive spot samples from 11 participants over three consecutive days, 33 samples of which were first morning voids (FMVs). We found 49 chemicals with detection frequencies over 70 % in all urine samples. Principal component analyses showed greater inter-person variations than each person's inter-day variations. Intraclass correlation coefficient (ICC) to assess the reproducibility of targeted chemicals demonstrated that regardless of sampling approaches, dichlorophenols, most parabens, benzophenones and triclosan showed moderate to high reproducibility (0.445 < ICC < 0.969), with relatively high predictive power of FMVs for 24-h collections. Notably, most phthalates, bisphenols and antioxidants showed low ICC values. Together, our work demonstrates that FMV samples may be adequate for assessing human exposure to parabens, benzophenones, triclosan and dichlorophenols, whereas multiple consecutive urine collections may be advantageous for evaluating exposure to most phthalates, bisphenols and antioxidants., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The nacre layer is composed of sheet-like aragonite crystals, with often loosely arranged polycrystal aragonite sheets which may induce poor mechanical properties in shells. In this study, a full-length low-complexity domain-containing protein (LCDP) cDNA from the triangle sail mussel Hyriopsis cumingii was generated and its role in shell formation investigated. The full-length cDNA was 1058 bp; it had an open reading frame (ORF) of 714 bp encoding 237 amino acids and contained a 20-amino acid signal peptide at the N-terminus and two low-complexity domains. H. cumingii LCDP was not homologous with other species. Tissue expression analyses showed that LCDP was specifically expressed in the mantle. In shell repair assays, significantly higher LCDP expression was observed in the shell repair group from days 12-21 (p < 0.01). After LCDP silencing, aragonite flake shapes in pearl layers became irregular with disordered deposition, while calcium carbonate (CaCO 3 ) crystal surfaces in prismatic layers became rougher and organic matrices between crystals appeared skeletonized, indicating the importance of biomineralization. Our in vitro CaCO 3 crystallization assays showed that LCDP induced single crystals to polycrystals, probably via loose arrangement between aragonite flakes. These results provide new insights on freshwater mollusk biomineralization and a theoretical basis for improved pearl quality., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

A new species of freshwater mussel belonging to the genus Pseudocuneopsis, namely Pseudocuneopsis wuana sp. nov., is diagnosed and described from Guangxi Province, China. This paper provides a detailed shell morphological description, soft-body anatomical characteristics, and partial sequences of mitochondrial COI as DNA barcode data for the novel species. The new species can be distinguished from its congeners (Pseudocuneopsis sichuanensis, P. yangshuoensis, and P. capitata) by shell shape, beak position, and surface sculpture. Phylogenetic analyses based on the mitochondrial COI gene reveal that Pseudocuneopsis wuana sp. nov. forms a sister group with P. yangshuoensis and exhibits an interspecific genetic distance of 5.1%. Therefore, we provide robust morphological and molecular evidence to support the validity of this new species. [ABSTRACT FROM AUTHOR]

Benthic bioaccumulation of hazardous materials has been a great challenge to the health of lake ecosystems. As representative benthic macroinvertebrates, freshwater mussels and their accumulation characteristics have been regarded as effective indicators for assessing potential risks induced by sedimentary metal(loid)s in lakes. Here we profile organ-specific accumulation of 35 metal(loid)s in a freshwater mussel (Hyriopsis cumingii) and their correlations to metal speciation in sediments of Poyang Lake, the largest lake of China. Significant organ-specific characteristics of metal accumulation were found in gills, though higher thallium (Tl) and selenium (Se) were found in the hepatopancreas, and greater arsenic (As) mostly accumulated in gonads. Pearson correlation analysis revealed that the bioaccumulation of silver (Ag), cobalt (Co), and rare earth elements (ΣREE) in gills and As in gonads were closely associated with those in bioavailable fraction of sediments. Based on the biochemical analysis in the major organs, gills exhibited the highest enzymatic activity compared with hepatopancreas and gonads. Sedimentary metals, particularly for available Ag, Co, and ΣREE, play key roles in causing lipid peroxidation in gills and significantly promote the activities of superoxide dismutase (SOD)/glutathione reductase (GR), while many metals (e.g., cadmium, manganese, Se) inhibit the glutathione (GSH) content in gonads and hepatopancreas. Our study indicates a high physiological sensitivity of mussels to these target metals, which highlights the significance of organ-specific accumulation of metal(loid)s in understanding the potential ecological risks of sedimentary metal(loid)s in lake ecosystems., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

A new species of freshwater mussel belonging to the genus Pseudocuneopsis, namely Pseudocuneopsis yangshuoensis sp. nov., is diagnosed and described from Guangxi Province, China. This paper provides a detailed morphological description, photograph of the type specimen, and anatomical characteristics along with partial sequences of mitochondrial COI as DNA barcode data for this novel species. The new species can be distinguished from its congeners (Pseudocuneopsis sichuanensis and Pseudocuneopsis capitata) by shell shape, beak position and surface sculpture. The interspecies genetic distance based on the COI barcode between P. yangshuoensis sp. nov. and P. sichuanensis is 8%, while it reaches 9% with P. capitata. Therefore, we provide robust morphological and molecular evidence to support the validity of this new species. [ABSTRACT FROM AUTHOR]

Poikilohydric autotrophs are the main colonizers of the permanent ice-free areas in the Antarctic tundra biome. Global climate warming and the small human footprint in this ecosystem make it especially vulnerable to abrupt changes. Elucidating the effects of climate change on the Antarctic ecosystem is challenging because it mainly comprises poikilohydric species, which are greatly influenced by microtopographic factors. In the present study, we investigated the potential effects of climate change on the metabolic activity and net primary photosynthesis (NPP) in the widespread lichen species Usnea aurantiaco-atra. Long-term monitoring of chlorophyll a fluorescence in the field was combined with photosynthetic performance measurements in laboratory experiments in order to establish the daily response patterns under biotic and abiotic factors at micro- and macro-scales. Our findings suggest that macroclimate is a poor predictor of NPP, thereby indicating that microclimate is the main driver due to the strong effects of microtopographic factors on cryptogams. Metabolic activity is also crucial for estimating the NPP, which is highly dependent on the type, distribution, and duration of the hydration sources available throughout the year. Under RCP 4.5 and RCP 8.5, metabolic activity will increase slightly compared with that at present due to the increased precipitation events predicted in MIROC5. Temperature is highlighted as the main driver for NPP projections, and thus climate warming will lead to an average increase in NPP of 167-171% at the end of the century. However, small changes in other drivers such as light and relative humidity may strongly modify the metabolic activity patterns of poikilohydric autotrophs, and thus their NPP. Species with similar physiological response ranges to the species investigated in the present study are expected to behave in a similar manner provided that liquid water is available., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)

The Chinese pond mussel Sinanodonta woodiana (Lea, 1834) (Bivalvia: Unionidae) is among the most invasive freshwater species worldwide. The last decades have seen its rapid geographical spread beyond the species' natural range, particularly in anthropogenically modified water bodies across Asia, America, and Europe where it is now very common. In this paper, we also confirm the presence of S. woodiana in Africa (Algeria) by establishing the UNESCO Biosphere Reserve and Ramsar site Oubeira Lake as a new locality for its occurrence. In all likelihood, S. woodiana was accidentally introduced in the 1980s with Asian fish species imported from Hungary for stocking purposes. The present survey was conducted in the summer of 2020, and here we present the first data on several biological aspects of 141 S. woodiana specimens collected in the lake fringe area. The age structure varied from two to over height years old; medium- and large-sized individuals with shell lengths ranging from 102.23 to 183.55 cm accounted for 96% of sampled mussels. A study of the conchological features revealed that bivalves adopt the species' typical morphological trends. Overall, our findings showed that S. woodiana succeeded in establishing a viable population in Oubeira Lake, which allows for the assumption that additional records can be predicted at a regional scale in locations related to the lake water system in Algeria and Tunisia. [ABSTRACT FROM AUTHOR]

In the present study, we evaluated the effects of different environments on the filtering rate (FR), mortality, and biodeposition (BD) of the freshwater mussel Unio douglasiae in bloom waters containing the toxic cyanobacterium Microcystis aeruginosa . The mean FR of 19 selected individuals (shell length, 5.0-9.8 cm) was 0.30 ± 0.03 L g -1  h -1 (range = 0.24-0.35 L g -1  h -1 ). Shell length was strongly correlated with both net and gross BD of mussels ( P < 0.0001). The mean FR was higher in river water (0.405 ± 0.052 L g -1  h -1 ) than in lake water (0.304 ± 0.051 L g -1  h -1 ). In contrast, the BD of mussels was higher in RW (0.671 ± 0.609 mg g -1  h -1 ) than in LW (0.275 ± 0.027 mg g -1  h -1 ). For algal species, the FR of mussels ranged from 0.114 ± 0.024 to 0.553 ± 0.019 L g -1  h -1 . The FR of U. douglasiae was higher in river water (mainly diatoms), whereas BD was higher in lake water (mainly Microcystis ). U. douglasiae did not prefer toxic M. aeruginosa , which was significantly accumulated in pseudofaeces and faeces. The maximum FR of U. douglasiae in algal bloom water was recorded at a water temperature of 25°C and water depth of 50 cm. Moreover, the in situ mortality of U. douglasiae was strongly affected by water temperature and nitrogen concentration. Overall, U. douglasiae can enhance water quality in eutrophic areas by removing dominant cyanobacteria, although its removal efficiency depends on environmental parameters and site of introduction., Competing Interests: The authors declare that there is no conflict of interest regarding the publication of this paper., (Copyright © 2022 Zhun Li et al.)

Infaunal freshwater mussels are highly threatened and declining worldwide. One of the potential threats to mussels consists of biological invasions. We intended to investigate the habitat overlap and behavioural differences between native (Unio pictorum, Unio tumidus, Anodonta anatina, Anodonta cygnea) and invasive (Asian Sinanodonta woodiana) unionid bivalves to determine potential sources of competition. Furthermore, we investigated differences between S. woodiana from the established population in artificially heated waters and from the recent population in a natural thermal regime. We used pairwise choice tests on mud, medium, coarse and very coarse sand, mixture of medium and coarse sand, fine, medium and coarse gravel, and observed mussel locomotion and burrowing in preferred and non-preferred substrata. All species generally preferred fine-grained materials. The widest preference range was exhibited by S. woodiana (both populations), whereas A. cygnea was the most selective. The preferences of the cold-water population of S. woodiana were shifted towards coarser materials compared to conspecifics from the heated waters, and highly overlapped with the preferences of the native species. Anodonta cygnea most often moved horizontally and spent the shortest time deeply burrowed. Both Unio species were deeply burrowed for the largest amount of time and the horizontal locomotion of U. tumidus was the lowest among the test species. Sinanodonta woodiana, especially from the heated water population, exhibited relatively weak locomotion (compared to A. cygnea) and burrowing (compared to Unio spp. and A. anatina). Deep burrowing was more common on fine-grained materials. Our results suggest that the native mussels can be threatened by S. woodiana due to their overlapping habitat preferences, potentially hindering habitat separation. However, mobile native mussels may be capable of migrating and avoiding competition. Accumulating knowledge of the biology and ecology of freshwater mussels could contribute to the creation and improvement of conservation plans to protect these threatened animals., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 The Authors. Published by Elsevier B.V. All rights reserved.)

The naiads, large freshwater mussels (Unionida), have very long life spans, are large-bodied, and produce thousands to millions of larvae (glochidia) which typically must attach to host fish tissues to metamorphose into a juvenile mussel. Glochidia develop within a female's marsupial gill demibranch, thus their number is restricted by female size. However, larger mussels acquire more energy, which could be invested in either larger-sized glochidia, in a more glochidia, or a combination of both. The high level of host specialization seen in many naiads may constrain glochidial size and shape around a narrow optimum, while naiads that use a wide range of host fishes may be predicted to possess greater plasticity in glochidial morphology. In this paper, we investigated the relationship between maternal body size and progeny body size and shape, aided by modern digital microscopy. We analyzed the between- and within- species variation of glochidia size and shape relative to female size in four widespread species of European naiads: Anodonta anatina, Anodonta cygnea, Unio crassus and Unio tumidus. Whereas the total reproductive output is collinear with female body size, substantial differences between species in glochidia size were found within genus Anodonta, but not genus Unio where glochidial size is remarkably consistent. The glochidial shape, however, differed within both Unio and Anodonta. We interpret this constant within-species glochidial size in Unio as reflecting a constraint imposed by the likelihood of successful transmission onto and off from a narrow range of hosts, whereas their shape seems to be less constrained. The Anodonta species, inhabiting a wide spectrum of habitats and using more than twice the number of fish hosts than Unio spp., have larger glochidia with greater variation in size and shape. Our results suggest that measures of glochidial variability may also serve as an indicator of host specificity in other naiads., (© 2021. The Author(s).)

The Chinese pond mussel, Sinanodonta woodiana, is non-native to European freshwater systems. Originating from Asia, it was brought to Europe in the 1970s and is now spreading across many countries. Management of the species is currently limited by a lack of information on the actual distribution and population characterisation of S. woodiana as well as on the co-occurrence of native mussels potentially resulting in competition. For this paper, we examined nine water systems in the German federal state of Bavaria with randomly observed and anecdotally reported S. woodiana occurrences. We recorded the density and biomass of S. woodiana and of the co-existing mussel species as well as the habitat characteristics. We found S. woodiana in eight water systems, co-existing with other native and invasive mussel species in seven of them. The distribution of S. woodiana was geographically widespread throughout Bavaria, indicating great invasion potential. In one fish pond, S. woodiana was the only mussel species occurring with the highest mean biomass (1286.0 ± 1067.7 g m−2) and with the biggest specimen (25.0 cm and 1616.0 g). The wide range of habitat variables matched the expectation of a wide ecological niche for the species. This study provides evidence that S. woodiana has already become established in many water systems in Bavaria, with fish ponds and fisheries management practises being a likely vector. To counteract this species and to conserve native mussel species, it is important to implement effective legislation, to take measures to eradicate this invasive mussel transnationally, and to raise public awareness. [ABSTRACT FROM AUTHOR]

Leonardo Fea, an Italian explorer and traveler, sampled a comprehensive collection of continental Mollusca during his travels throughout the former British Burma (currently Myanmar) in 1885-1887. Cesare Maria Tapparone-Canefri, an Italian malacologist, studied this sample and published a paper with a description of numerous terrestrial and freshwater molluscan taxa new to science. This collection was partly deposited in the Museo Civico di Storia Naturale di Genova (MSNG), Italy and the Indian Museum (ZSI: Zoological Survey of India) in Kolkata. Here, we provide a re-analysis of C.M. Tapparone-Canefri's Burmese Unionidae collection. Our study reveals that the type series of only four nominal taxa described by Tapparone-Canefri as new to science in 1889 are still available in the MSNG, i.e. Unio rectangularis, U. pulcher, U. protensus var. obtusatus, and U. marginalis var. subflabellata. The first taxon is a valid species belonging to the genus Yaukthwa, while U. pulcher and U. protensus var. obtusatus are considered here as junior synonyms of the widespread Lamellidens generosus, and the last nominal taxon corresponds to L. savadiensis. The MSNG collection also contains shell lots of Indochinella pugio pugio, I. pugio paradoxa, Indonaia andersoniana, Radiatula chaudhurii, R. mouhoti haungthayawensis, Lamellidens savadiensis, L. generosus, Yaukthwa nesemanni, and Y. zayleymanensis, most of which were listed in Tapparone-Canefri's work under incorrect names. We revise all the freshwater mussel taxa listed by Tapparone-Canefri based on the original descriptions, available DNA sequences, morphological data, and biogeographic evidence. A freshwater mussel from the Haungthayaw River that was identified by Tapparone-Canefri as Unio exolescens is described here as Trapezoideus mitanensis sp. nov., a fourth species in this small Contradentini genus with a restricted range. Finally, new taxonomic opinions are proposed here for Leoparreysia tavoyensis, Trapezidens dolichorhynchus, Lamellidens generosus, and Lamellidens savadiensis. [ABSTRACT FROM AUTHOR]

Copyright of Acta Oecologica Carpatica is the property of Acta Oecologica Carpatica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Before this study, researchers had not systematically surveyed the Río Conchos, a tributary of the Rio Grande located in northern Mexico, for freshwater mussels. The Texas hornshell, Popenaias popeii, an endangered species under the United States Endangered Species Act, occurs in the main stem of the Rio Grande near its confluence with the Río Conchos. The Texas hornshell's proximity to the Río Conchos prompted us to survey to determine whether P. popeii also occurs within the Conchos basin. Additionally, previous researchers described the Conchos disk, Disconaias conchos, from the Río Conchos but, to date, no one has reported live individuals of this species. The goal of this study was to determine the status of mussels within the Río Conchos basin and to provide a baseline for future monitoring efforts. We qualitatively surveyed 11 sites within the Río Conchos basin in May 2018. In total, we found two live individuals of the paper pondshell, Utterbackia imbecillis, at one site in the Río San Pedro, a tributary of the Conchos River, and as shells of recently live individuals at two sites in the Río Conchos. We found D. conchos as relict shells only at three sites, two in the Río Conchos and one in a tributary of the river at Coyame. The lack of live or fresh-dead material suggests that D. conchos is extinct. We also found live individuals of nonnative Asian clams (Corbicula spp.) at 10 sites. Sand and gravel mining, high organic pollution, and inadequate instream flows were evident throughout the basin and might explain the general absence of mussels. [ABSTRACT FROM AUTHOR]

Securing adequate supply of high-quality water is of increasing global importance and relies in large part on ecosystem services provided by freshwater biota. Unionid mussels are important keystone species and habitat engineers that shape freshwater ecosystems through water filtration, nutrient cycling and provision of habitats; their rapid global declines result in dramatic losses of ecosystem functions. Maintenance and enhancement of the services they provide depend on the identification of their crucial habitats. Following theoretical assumptions, this study analyses the importance of lake-stream transition zones for unionid mussels, based on data collected in 1984 and 2019 from an undisturbed stream flowing through five consecutive lakes. Mussel distribution matched the distribution of host fish and was strongly influenced by lakes: densities were highest near lake outlets, reaching 290 ind. m -2 (14.7 kg m -2 ) in 2019, and declined with downstream distance following a negative power function. This pattern was spatially consistent and sustained over time. All six unionid species native to north-central Europe were present, but common species (Anodonta anatina, Unio pictorum, U. tumidus) contributed about 80% of individuals and were responsible for most of the ecosystem services provided by unionid mussels. Estimated 1.9 × 10 6 mussel individuals inhabiting 3.2 km of stream length filtered a water volume equivalent to the total stream discharge approximately 2.5 times daily. Aggregations of spent shells, up to 17 kg m -2 , accumulated downstream of lakes, forming extensive shell and mussel beds, providing habitats and contributing shell hash that improved stream-bed conditions. Globally invasive Dreissena polymorpha was present at low densities and did not spread or increase in abundance, indicating a long-term biotic resistance of the natural native community. Our study underscores the importance of undisturbed lake outlets, longitudinal connectivity of riverine ecosystems, and of common mussel species in maintaining freshwater ecosystem functionality and provision of vital services., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Naphthalene sulfonic acids (NSAs) are used primarily as additives in a wide range of industrial products (e.g., rubber materials, coatings, sealants, fuels, paints). Based on modeled physicochemical properties, NSAs would likely partition into sediments or the tissues of biota in an aquatic system. This study examined the potential for three NSAs, dinonylnaphthalene disulfonic acid (DNDS), barium dinonylnaphthalene sulfonate (BaDNS), and calcium dinonylnaphthalene sulfonate (CaDNS), to accumulate in the tissue of a freshwater mussel (Lampsilis siliquoidea) and oligochaete worm (Tubifex tubifex). The ability of L. siliquoidea to depurate accumulated chemical was also assessed. Mussels were exposed via sand spiked with CaDNS for 25 d, and then transferred to clean water where their ability to depurate the chemical over an additional 28 d was monitored. Worms were exposed to each of the three NSAs via spiked sediment for 28 d. NSA concentrations were measured separately in gill, foot, and remaining soft tissues (viscera) for mussels and in whole body tissue samples of worms. For L. siliquoidea, the largest concentration of CaDNS was measured in the gill tissue; once removed from CaDNS exposure, mussels were able to depurate up to 87% of the CaDNS from their tissues in 28 days. The biota-sediment accumulation factors (28-d BSAFs) for T. tubifex were 2.8-5.2, 0.53-0.76, and 0.83-1.11 for DNDS, BaDNS, and CaDNS, respectively. For mussel gill and viscera, BCF K values were 14.07 and 16.39, respectively. When BAF K s were calculated using the concentration of CaDNS in sand, they were 1.11 and 1.29 for mussel gill and viscera, respectively. These values are much lower than what would be necessary to classify this chemical as bioaccumulative; however, the BSAFs for DNDS in T. tubifex indicated a potential biomagnification concern if this compound were to occur in the aquatic environment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Crown Copyright © 2020. Published by Elsevier Ltd. All rights reserved.)

Although eutrophication of freshwaters is a natural process, the human impact often leads to inland waters becoming overloaded with nutrients, impoverishing many valuable and vanishing habitats, such as floodplain lakes. These changes need to be reversed if the occurrence of endangered aquatic species is to be restored. In this paper we analyse the impact of a change in the water regime of a naturally eutrophic floodplain lake, which harbours a large diversity of Unionidae (large freshwater mussels), a globally threatened taxonomic group that provides important ecosystem functions and services. We found that a slight increase in the discharge from this waterbody, following the construction of an additional outflow pipe, positively influenced recruitment in three of the five mussel species inhabiting the lake. We also found that, after the construction of this additional outflow, the niches of juveniles of Anodonta cygnea and Unio spp. changed, revealing differences in their hydrological requirements. Our results suggest that, as in lotic habitats, complex hydraulic parameters are highly significant to unionid mussels in lentic conditions., (Copyright © 2019 The Authors. Published by Elsevier B.V. All rights reserved.)

Bivalves are ubiquitous members of freshwater ecosystems and responsible for important functions and services. The present paper revises freshwater bivalve diversity, conservation status and threats at the global scale and discusses future research needs and management actions. The diversity patterns are uneven across the globe with hotspots in the interior basin in the United States of America (USA), Central America, Indian subcontinent and Southeast Asia. Freshwater bivalves are affected by multiple threats that vary across the globe; however, pollution and natural system (habitat) modifications being consistently found as the most impacting. Freshwater bivalves are among the most threatened groups in the world with 40% of the species being near threatened, threatened or extinct, and among them the order Unionida is the most endangered. We suggest that global cooperation between scientists, managers, politicians and general public, and application of new technologies (new generation sequencing and remote sensing, among others) will strengthen the quality of studies on the natural history and conservation of freshwater bivalves. Finally, we introduce the articles published in this special issue of Hydrobiologia under the scope of the Second International Meeting on Biology and Conservation of Freshwater Bivalves held in 2015 in Buffalo, New York, USA. [ABSTRACT FROM AUTHOR]

We diagnose and describe a new freshwater mussel species of the genus Inversidens, I. rentianensis sp. nov. from Jiangxi Province, China based on morphological characters and molecular data. This paper includes a morphological description and photograph of the holotype, and partial sequences of mitochondrial COI as DNA barcode data. [ABSTRACT FROM AUTHOR]

Light affects bivalve behavior and gaping activity, but its potential effects on bivalve filtration remain poorly investigated. In this study, clearance rates of two bivalve species: the Asian clam, Corbicula fluminea and the paper pondshell, Utterbackia imbecillis, were assessed in light (6.5 ± 0.5 µmol m−2 s−1) and dark (0.0 µmol m−2 s−1) conditions. We found that clearance rates remained similar between C. fluminea (50 ± 18 mL g−1 h−1) and U. imbecillis (41 ± 10 mL g−1 h−1) during light conditions. However, C. fluminea (110 ± 15 mL g−1 h−1) filtered significantly faster than U. imbecillis (24 ± 6 mL g−1 h−1) in the dark condition (p < 0.05). The results indicated that light might affect the filtration activity in freshwater bivalves differently, depending on species. [ABSTRACT FROM AUTHOR]

Arnold Ortmann, Curator of Invertebrate Zoology at Carnegie Museum of Natural History in Pittsburgh, Pennsylvania during the early 20th century, and the foremost American freshwater malacologist of his time, made important contributions to the study of mollusks in Virginia, especially freshwater mussels. His final collecting trips to the Commonwealth occurred during the fall of 1925 and 1926, but he died in January 1927 and never published the results of these surveys. This paper includes a reconstruction of Ortmann's itinerary based on voucher specimen records and a summary of his collecting results for all mollusks obtained during these trips to eastern and southcentral Virginia. Several of the freshwater mussel species collected by Ortmann are now rare and declining, and no longer inhabit the areas where he documented them. [ABSTRACT FROM AUTHOR]

Freshwater bivalves (Bivalvia, Unionida, Unionidae) are among the most threatened groups of animals in the world. Taxonomic uncertainties pose a particular challenge due to significant intraspecific variation and apparent plasticity in shell morphology among these species, impeding efficient conservation planning and management. The species Unio szechenyii that is endemic to China has long been regarded as a synonym for Cuneopsis heudei due to the high convergence in shell morphology. The recently validated species Middendorffinaia mongolica is currently restricted to the Amur Basin and Primorye in eastern Russia. This species is classified under the tribe Middendorffinaiini of the subfamily Unioninae within the family Unionidae based on multilocus phylogeny. However, the lack of comprehensive taxonomic information and sufficient molecular phylogenetic data casts uncertainty on the validity and taxonomic status of these two species. We aim to reassess the validity of Unio szechenyii and confirm the taxonomic status of Middendorffinaia mongolica , a new record for China, by integrating taxonomy with robust mitochondrial phylogenomics. We support the validity of Unio szechenyii and propose a recombination as Cuneopsis szechenyii comb. nov. by integrating shell morphometry, soft-body anatomy and molecular evidence. By determination of the mitochondrial genome of Cuneopsis szechenyii , Cuneopsis kiangsiensis , Middendorffinaia mongolica and Pseudocuneopsis wuana , we elucidate intrageneric relationships within the genera Cuneopsis and Pseudocuneopsis. In addition, based on the updated consensus taxonomic framework including tribes and subtribes in Unioninae, mitochondrial phylogenomics strongly support the transfer of Middendorffinaia mongolica from the tribe Middendorffinaiini to the tribe Unionini and classification under the subtribe Middendorffinaiina stat. rev. ZooBank: The maternal mitochondrial genomes of Unio szechenyii , Cuneopsis kiangsiensis , Middendorffinaia mongolica and Pseudocuneopsis wuana are sequenced. The validity of Unio szechenyii , previously considered a synonym of Cuneopsis heudei , is supported by the integration of conchometry, soft-body anatomy and molecular evidence, and a recombination as Cuneopsis szechenyii comb. nov. is proposed. The intrageneric relationships within the genera Cuneopsis and Pseudocuneopsis are elucidated based on the mitochondrial phylogenomics. Middendorffinaia mongolica , a new record for China, is proposed for transfer from the tribe Middendorffinaiini to the tribe Unionini and classification under the subtribe Middendorffinaiina stat. rev. (Image credit: Ruiwen Wu.) [ABSTRACT FROM AUTHOR]

Niche partitioning promotes species coexistence. Yet, it remains unclear how phylogeny and morphology influence the trophic niches of closely related aquatic species with shared feeding modes. Freshwater mussels (Family: Unionidae) are a group of filter‐feeding bivalves that are ideal for investigating mechanisms of niche partitioning. Particle size selection and patterns of ingestion are controlled by gill latero‐frontal cirri density (CD) and the number of cilia per cirrus (CC). We investigated trophic assimilation and niche area using stable isotope signatures (훿13C and 훿15N) and gill morphology with scanning‐electron microscopy for a diverse mussel assemblage from the Sipsey River, Alabama, USA. We predicted that (1) trophic niches and gill morphology would differ within and among species across sites; (2) co‐occurring species would partition food resources; (3) greater phylogenetic distances among species would result in increased trophic dissimilarity; (4) more CC and higher CD would result in a narrower trophic niche area, or more constrained range of food items assimilated. We found that (1) species identity and site influenced gill morphology and stable isotope signatures but that the trophic niche area of a species was only affected by species identity; (2) the average proportion of niche area overlap between co‐occurring species was low across sites (0.04 to 0.18); (3) trophic dissimilarity among species increased with phylogenetic distance; (4) CD but not the number of CC negatively related to trophic niche area. Our results indicate that gill morphology and evolutionary history are likely key factors governing the trophic niches of mussels. In addition, intraspecific variation in gill morphology across sites may either reflect a phenotypic response to differences in local resource availability or suggest that other mechanisms shape particle selection. Examining the interplay among the trophic niche, phylogeny, and morphology among functionally similar species further informs our understanding of the mechanisms facilitating their coexistence. [ABSTRACT FROM AUTHOR]

Copyright of Natura Sloveniae: Revija za Terensko Biologijo / Journal of Field Biology is the property of Natura Sloveniae and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Freshwater bivalves have been highly threatened by human activities, and recently their global decline has been causing conservational and social concern. In this paper, we review the most important research events in freshwater bivalve biology calling attention to the main scientific achievements. A great bias exists in the research effort, with much more information available for bivalve species belonging to the Unionida in comparison to other groups. The same is true for the origin of these studies, since the publishing pattern does not always correspond to the hotspots of biodiversity but is concentrated in the northern hemisphere mainly in North America, Europe and Russia, with regions such as Africa and Southeast Asia being quite understudied. We also summarize information about past, present and future perspectives concerning the most important research topics that include taxonomy, systematics, anatomy, physiology, ecology and conservation of freshwater bivalves. Finally, we introduce the articles published in this Hydrobiologia special issue related with the International Meeting on Biology and Conservation of Freshwater Bivalves held in 2012 in Bragança, Portugal. [ABSTRACT FROM AUTHOR]

The proteins of Smad family are critical components of the TGF-β superfamily signal pathway. In this paper, we cloned two intracellular mediators of TGF-β signaling, Smad3 and Smad5, from the pearl mussel Hyriopsis cumingii. The full length cDNA of HcSmad3 and HcSmad5 were 2052 bp and 1908 bp and encoded two polypeptides of 418 and 461amino acid residues, respectively. The deduced amino acid of HcSmad3 and HcSmad5 possessed two putative conserved domains, MH1 and MH2, a conserved phosphorylation motif SSXS at the carboxyl-terminal. The two Smad genes were detected muscle, mantle, hepatopancreas and gill, but with a very low level in heamocytes. The transcripts of Smad3 and Smad5 were up-regulated in hemocytes and hepatopancreas after A. hydrophila and PGN stimulation. However, the expression of Smad3 and Smad5 were only up-regulated in hepatopancreas after A. hydrophila stimulation. The transcripts of Smad3 and Smad5 had a slight change in hepatopancreas after PGN stimulation. The transcripts of HcSmad3 showed very little increase and HcSmad5 mRNA significantly up-regulated after wounding., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

This paper reports the results of the first statewide survey of the freshwater mussels of Nebraska. Survey goals were: (1) to document current distributions through collection of recent shells; (2) to document former distributions through collection of relict shells and examination of museum collections; (3) to identify changes in distribution; (4) to identify the primary natural and anthropomorphic factors impacting unionids; and (5) to develop a model to explain the documented distributions. The survey confirmed 30 unionid species and the exotic Corbicula fluminea for the state, and museum vouchers documented one additional unionid species. Analysis of museum records and an extensive literature search coupled with research in adjacent states identified 13 additional unionid species with known distributions near the Nebraska border. Some of these unionids may have formerly inhabited the state. Seven documented species have probably been extirpated, and the ranges of 15 others have contracted significantly. Only nine species are relatively stable at present, and one of these is extremely rare and federally endangered. Diversity is concentrated in the formerly glaciated portion of eastern Nebraska, and drops abruptly along the Missouri River to the east and in the Great Plains westward. The primary natural factors influencing unionid distributions in Nebraska include availability of perennially flowing waters, host fish diversity, substrate composition and stability, and formerly heavy sediment loads. Anthropomorphic factors are surface and subsurface irrigation withdrawals, construction of canals and reservoirs, channelization, erosion, intensive grazing, contaminants, and the introduction of invasive species. Unionid presence and diversity largely correlates with substrate stability. Stream orientation and morphology in portions of eastern Nebraska promote slow currents, and substrates composed of mud, sand, and rock provide greater stability than the shifting sand substrates common elsewhere in the state. In central and western Nebraska, unionid populations are concentrated in headwaters, backwaters, and side-channels of rivers, and canals, reservoirs, and small tributaries, while the generally shifting sand habitats of most rivers provide relatively little viable habitat. In the historic Missouri River, unstable substrates and (formerly) heavy sediment loads limited diversity to silt tolerant species, and viable habitat largely to backwaters, sloughs, attached lakes, side channels, and relatively few main channel environments. Today, upstream dams have greatly reduced the sediment load in the Missouri River, but unstable substrates restrict mussels to backwaters, side channels, pools below wing dams, revetments, and other areas sheltered from strong currents. Channelization and erosion/sedimentation have destroyed or drastically impacted stream habitats in eastern Nebraska resulting in the loss of much of the original unionid diversity. Surface and subsurface irrigation coupled with related declines in water tables have eliminated habitat in western Nebraska, though losses are partially compensated for some species by colonization of viable reaches of newly created impoundments and canals. Intensive grazing along streams and agricultural pollution further exacerbate habitat degradation and pressure remaining unionid populations. Invasive species directly compete with native mussels for sustenance and living space and may become serious threats to the survival of remaining unionid species in some habitats. [ABSTRACT FROM AUTHOR]

Polyacrylamide has become an effective tool for reducing construction-related suspended sediment and turbidity, which are considered to have significant adverse impacts on aquatic ecosystems and are a leading cause of the degradation of North American streams and rivers. However, little is known about the effects of polyacrylamide on many freshwater organisms, and prior to the present study, no information existed on the toxicity of polyacrylamide compounds to native freshwater mussels (family Unionidae), one of the most imperiled faunal groups globally. Following standard test guidelines, we exposed juvenile mussels (test duration 96 h) and glochidia larvae (test duration 24 h) to 5 different anionic polyacrylamide compounds and 1 non-ionic compound. Species tested included the yellow lampmussel ( Lampsilis cariosa), an Atlantic Slope species that is listed as endangered in North Carolina; the Appalachian elktoe ( Alasmidonta raveneliana), a federally endangered Interior Basin species; and the washboard ( Megalonaias nervosa), a common Interior Basin species. We found that median lethal concentrations (LC50s) of polyacrylamide ranged from 411.7 to >1000 mg/L for glochidia and from 126.8 to >1000 mg/L for juveniles. All LC50s were orders of magnitude greater (2-3) than concentrations typically recommended for turbidity control (1-5 mg/L), regardless of their molecular weight or charge density. The results demonstrate that the polyacrylamide compounds tested were not acutely toxic to the mussel species and life stages tested, indicating minimal risk of short-term exposure from polyacrylamide applications in the environment. However, other potential uses of polyacrylamide in the environment (e.g., wastewater treatment, paper processing, mining, algae removal) and their chronic or sublethal effects remain uncertain and warrant additional investigation. Environ Toxicol Chem 2017;36:2715-2721. Published 2017 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America. [ABSTRACT FROM AUTHOR]

During an epidemiological survey following a mortality event of freshwater mussels in 2018 in the Embarrass River, Wisconsin, USA, we identified a novel microsporidian parasite in the ovaries of mucket (Actinonaias ligamentina), plain pocketbook (Lampsilis cardium), and fatmucket (Lampsilis siliquoidea) (Unionidae). Histopathology showed round-to-oval microsporidian spores in the cytoplasm of oocytes in 60% (3/5) of female mucket, 100% (4/4) of female plain pocketbook, and 50% (1/2) of female fatmucket. Using transmission electron microscopy, we found that mature spores were round-to-oval and measured 4.13 ± 0.64 µm (3.14–5.31) long by 2.88 ± 0.37 µm (2.36–3.68) wide. The spores had a thin electron-dense exospore with a spiky "hairy" coat, a thick electron lucent endospore, diplokaryotic nuclei, a polar vacuole, and 27–28 polar filaments arranged in 1–3 rows. Sequencing of the small subunit rRNA produced a 1356 bp sequence most similar to that of Pseudonosema cristatellae (92%), and phylogenetic analysis grouped it within the freshwater Neopereziida. Genetic, morphological, and ultrastructural characteristics did not closely match those of other Pseudonosema spp., and a new genus and species, Hirsutonosema embarrassi n. gen. n. sp., were designated. Additional studies could evaluate host susceptibility, distribution, seasonality, transmission, and lethal or sub-lethal effects of this parasite on freshwater mussels. [ABSTRACT FROM AUTHOR]

Effective species conservation necessitates the ability to accurately differentiate among species, a challenge compounded by taxonomic uncertainties in freshwater mussels due to substantial intraspecific variation and pronounced phenotypic plasticity in shell morphology. The taxonomic status and species validity of Scabies longata and S. chinensis, two species endemic in China, have been under continuous debate since establishment. The lack of essential molecular data required for a comprehensive systematic study has resulted in the unresolved taxonomic status of these two species. This study presents molecular data, including COI barcoding, COI + 28S rRNA, and mitogenomic data combined with morphological characteristics to assess the validity of S. longata and S. chinensis. Both morphological and COI barcoding data support the conclusion that S. longata and S. chinensis are junior synonyms of Nodularia douglasiae and N. nuxpersicae respectively. Our findings suggest the absence of Scabies species in China. Mitochondrial phylogenetic analyses were used to further elucidate intrageneric relationships within the genus Nodularia, revealing the following relationships: (N. breviconcha (Nodularia sp. 1 (N. douglasiae (N. nuxpersicae, N. nipponensis)))). We underscore the significance of employing an integrated taxonomic approach for species identification, especially given the considerable morphological disparities between larvae and adult freshwater mussels. Proper morphological identification of adult specimens is essential for extracting meaningful taxonomic characters. Furthermore, our findings suggest a notable resemblance between the freshwater bivalve fauna in southern China and those east of the Mekong River. [ABSTRACT FROM AUTHOR]